The CEA-Leti antenna laboratory has developed DEVIN, a miniaturized personal exposimeter capable of continuously measuring, under real-life conditions, the power emitted by a smartphone as well as its distance from the body. Designed at the request of ANSES to provide reliable data to WHO epidemiologists, this instrument, already tested on 300 volunteers and subsequently adapted to 5G as part of the Seawave project, showcases CEA-Leti's expertise in miniaturization and instrumentation in support of public health research.

Until now, studies on the impact of electromagnetic waves from mobile phones have relied on laboratory experiments based on a worst-case scenario. Epidemiological studies, meanwhile, have been based on self-reported questionnaires, without any objective measurement of actual exposure.

Measuring emitted power and distance from the body

To address this gap, ANSES (the French Agency for Food, Environmental and Occupational Health & Safety) commissioned CEA-Leti to design a measurement instrument. The objective? To provide WHO epidemiologists with reliable data on people's actual exposure when using their phones.

“We designed the DEVIN instrument to continuously measure exposure parameters to electromagnetic waves, namely the power emitted by the source and its distance from the body, which are essential for the analysis," explains Serge Bories, research engineer at CEA-Leti.

This is known as an “uplink" exposimeter, as it specifically measures the signal emitted by the mobile phone. The phone can transmit up to 200 milliwatts of power, much less than base station antennas. The difference is that it is used very close to the body, either in contact with the skin or close to the brain.

Innovation through miniaturization

CEA-Leti's innovation lies in integrating a complete system into a miniaturized device. DEVIN was reduced to the size of a credit card, with a thickness of just one centimeter, so that it can be attached to the back of a phone.

It records ten measurements per second, including transmitted power, frequency band, and the position of the transmitting antenna relative to the body, making it possible to determine how energy is distributed within the body.

“Our exposimeter was tested during the ANSES Coriolis measurement campaign involving 300 volunteers in France and was also tested by various research institutes across Europe," says Serge Bories.

The results revealed significant variations in exposure levels. For example, a phone call with the handset held against the ear results in greater exposure than sending a text message, while greater distance from a base station increases uplink exposure.

The weaker the radio link between the transmitter and receiver, the more power the phone uses to maintain its connection to the network. However, all measurements remained well below the regulatory exposure limits.

Looking ahead to 6G

The European Seawave project, led by the University of Thessaloniki and involving several partners, including CEA-Leti, has taken this work a step further with the development of a 5G-compatible version of DEVIN.

This version can detect different antennas integrated into recent smartphones and has a battery life of several days.

The exposimeter does not depend on mobile network operators or specific phone models. It directly measures physical quantities, without relying on telecommunications signals, which differ from one mobile technology generation to another.

“This technological independence is another major innovation of DEVIN," notes Serge Bories. “It will allow us to use it with future generations of mobile technology," including 6G.

This research has led to the publication of several scientific papers and provides epidemiologists with a tool to catch up with the rapid deployment of mobile networks, thanks to an instrument adapted to 5G mobile communications.

“The story does not end here," says the researcher.                                                                                                                                                     “We are already working toward a future version of DEVIN compatible with 6G."

Above all, beyond the technical achievement, this research demonstrates CEA-Leti's ability to develop technology in response to societal needs.